Drug-drug interaction of amlodipine with selected co-prescribed medications

Abstract

This study evaluated the pharmacokinetic and pharmacodynamic interactions between amlodipine and three commonly co-administered drugs: loratadine, artemether-lumefantrine, and diclofenac. A total of 120 hypertensive participants were randomly assigned into three groups (n=40 per group) based on the co-administered drug with amlodipine. Baseline demographic and clinical characteristics, including age, gender, and hypertension duration, showed no statistically significant differences among the groups (p > 0.05).Pharmacokinetic analysis revealed variations in the plasma concentration of amlodipine depending on the co-administered drug. Notably, co-administration with loratadine resulted in slightly increased amlodipine plasma levels at all time points, whereas artemether-lumefantrine significantly reduced amlodipine exposure, as evidenced by a lower area under the curve (AUC). Diclofenac caused a moderate reduction in amlodipine levels.Pharmacodynamic evaluation after 4 weeks of treatment indicated significant differences in blood pressure (BP) control among groups. The amlodipine + loratadine group achieved the highest BP reduction, while the amlodipine + artemether-lumefantrine group showed significantly attenuated BP control (p < 0.05).Adverse drug reactions (ADRs) were assessed using the Naranjo causality scale. The most frequently reported ADRs included dizziness, nausea, edema, and palpitations, with higher incidences observed in the amlodipine + artemether-lumefantrine group.In conclusion, drug-drug interactions significantly influence the bioavailability and therapeutic outcomes of amlodipine. Loratadine appears to enhance amlodipine's efficacy, while artemether-lumefantrine diminishes it. These findings underscore the need for careful selection of co-medications in hypertensive patients to optimize treatment outcomes and minimize adverse effects.